Breaking of seed dormancy in a Turkish endemic Hypericum species: Hypericum aviculariifolium subsp. depilatum var. depilatum by light and some pre-soaking treatments

The aim of this study was to enhance the germination rate of Hypericum aviculariifolium subsp. depilatum var. depilatum seeds, which have a low germination rate under normal laboratory conditions. The seeds were soaked for 30 min in 50, 100 or 150 ppm GA solution, tap water, 40, 50 or 60 °C hot water before placing in Petri dishes. For KNO3 treatment, seeds imbibed in 20 ml KNO3 (0.01 mol) in Petri dishes. To evaluate the effect of light on germination rate, the study was performed under both continuous illumination and darkness in a growth chamber. Light was the most important factor in seed germination in H. aviculariifolium. Light, tap water and GA 50 ppm treatments significantly enhanced germination. In darkness, only the seeds treated with KNO3 germinated effectively. Results revealed that H. aviculariifolium subsp. depilatum var. depilatum seeds have exogenous dormancy and a light requirement for germination. In order to overcome exogenous dormancy originating from a chemical inhibitor in the capsule and seed coat, soaking in tap water is recommended. KNO3 at a rate of 0.01 mol treatment was an effective alternative to the seeds light requirements.